Hi Shekinah,
I also have children who are tall for their ages and have experienced similar vacation planning questions with my own children. The official policy for
Walt Disney World recommended attire is located in this link. In this link for attire guidelines there is a stipulation regarding attire not appropriate for the parks for
adults dressing in costume (except for certain events such as Mickey's Not-So-Scary Halloween Party), however this stipulation is limited to adults.
In my opinion, if your child is not yet a teen and still wishes to dress in a costume, then count your blessings and enjoy this precious moment with her! In fact she is still young enough to enjoy a Princess Makeover at Bibbidi Bobbidi Boutique which offers makeovers and costumes for children ages 3-12. I have an 11 year old (very tall) daughter myself and she is still very much into dressing up when she visits the Disney Parks. As my daughter grows older she is naturally trending towards Disney inspired outfits rather than complete replica costumes, but she still loves to wear tiaras and have a great updo while visiting the theme parks. Whether your daughter wishes to dress in costume or have a Disney inspired outfit, she should be just fine and be within the Disney Parks attire guidelines.
Enjoy your Magical Moments with your little Princess Shekinah. These are the moments you will always hold dear to your heart.
Blessings,
Brenda ºOº